The invention concerns a device for conducting electrochemical measurements in glass or salt melts with a least one indicator electrode and one reference electrode arrangement.
Such devices are widely known, especially from GB 2 057 695. Here, a measurement of the oxygen partial pressure takes place by means of an electrochemical measuring cell, also called the reference electrode arrangement, which is connected with an indicator electrode through a typical indicator and/or evaluating facility (measuring system). A platinum wire is used as the indicator electrode, which is passed through an aluminum oxide body. The platinum wire is freely exposed at the tip of the aluminum oxide body, so that it can come into contact indicator with the melt as soon as the indicator electrode dips into this. The aluminum oxide body is mounted in an aluminum oxide tube. In practice, it has become apparent that it is not possible to create a gas-tight lead-through between the platinum electrode and the aluminum oxide body. In this way, oxygen from the atmosphere above the melt penetrates to the part of the indicator electrode which stands in contact with the melt, so that the values measured there do not correspond to the actual conditions within the melt, and the measurement is thereby erroneous.
Similar measurement arrangements are known, for example, from DE 38 11 915 A1. Here too, the indicator electrode is made of platinum.
The determination of iron, sulfur or chromium in glass melts by voltametric analysis with three electrodes is known, for example, from Glastech. Ber. Glass Sci. Technol. 68(9), pages 273-277 (1995). Even here, the problems mentioned occur. Thus, for example, the size of the electrode surface in the glass must be known exactly.